Please note: The present advice replaces the catch advice given for 2017 (in September 2016) and the catch advice given for 2018 (in September 2017).

Transcription

1 ICES Advice on fishing opportunities, catch, and effort Northeast Atlantic and Arctic Ocean Published 29 September 2017 Version 2: 30 October 2017, Version 3: 23 January 2018 DOI: /ices.pub.3392 Herring (Clupea harengus) in subareas 1, 2, and 5, and in divisions 4.a and 14.a, Norwegian spring-spawning herring (the Northeast Atlantic and the Arctic Ocean) ICES stock advice Please note: The present advice replaces the catch advice given for 2017 (in September 2016) and the catch advice given for 2018 (in September 2017). ICES advises that when the long-term management plan agreed by the EU, Faroe Islands, Iceland, Norway, and Russia in 1999 is applied, catches in 2017 should be no more than tonnes. ICES advises that when the long-term management plan agreed by the EU, Faroe Islands, Iceland, Norway, and Russia in 1999 is applied, catches in 2018 should be no more than tonnes. Stock development over time Fishing mortality has had an overall declining trend since 2010 and was well below FMSY in The stock is declining and estimated to be below MSY Btrigger since Since 1998 four large year classes have been produced (1998, 1999, 2002, and 2004). All year classes since 2005 are estimated to be average or small. Figure 1 Herring in subareas 1, 2, and 5, and in divisions 4.a and 14.a (Norwegian spring-spawning herring). Summary of the stock assessment. Confidence intervals (95%) are included in the recruitment, fishing mortality, and spawning-stock biomass plots. FW is the fishing mortality weighted by the population numbers. Version 2: In October 2017, an error was detected in the conversion of acoustic data from the Norwegian acoustic survey on the spawning grounds survey index ( Fleet 1 ) for the period ; the error meant that abundance indices from this period had been significantly underestimated. The error affected both the advice for 2017, issued in September 2016, and that for 2018, issued in September The corrected catch advice for 2017 and 2018 is based on the corrected 2017 assessment. The corrected assessment results in a 14% downwards revision of the SSB value in 2017 and a 15% upwards revision of the F value in 2016 relative to the assessment used for the advice released in September Applying the long-term management plan results in a 32% downwards revision relative to the previously released catch advice for 2017 and a 30% downwards revision relative to the previously released catch advice for Version 2: plots updated to reflect the corrected assessment. ICES Advice

2 Stock and exploitation status Table 1 Herring in subareas 1, 2, and 5, and in divisions 4.a and 14.a (Norwegian spring-spawning herring). State of the stock and fishery relative to reference points. Catch options for 2018 Table 2 Herring in subareas 1, 2, and 5, and in divisions 4.a and 14.a (Norwegian spring-spawning herring). The basis for the catch options. Variable Value Source Notes F ages 5 11 (2017) ICES (2017) Based on ICES estimated catches SSB (2018) t ICES (2017) R age2 (2017) thousand ICES (2017) Estimated by XSAM. Median of stochastic recruitment estimated by XSAM, based on the R age2 (2018) thousand ICES (2017) years Catch (2017) t ICES (2017) Sum of declared national quotas. Table 3 Herring in subareas 1, 2, and 5, and in divisions 4.a and 14.a (Norwegian spring-spawning herring). Annual catch options. All weights are in tonnes. Basis Total catch (2018) FW (2018)* SSB (2019) % SSB change ** % Catch change *** ICES advice basis Agreed management plan^ Other options MSY approach: FMSY SSB(2018)/MSY Btrigger FMSY F = Fpa Flim^^ SSB (2019) = Blim SSB (2019) = Bpa = MSY Btrigger ^^^ F = F * F w = Fishing mortality weighted by population numbers (age groups 5 11). ** SSB 2019 relative to SSB *** Catch in 2018 relative to estimated catch in 2017 ( t). ^ According to the harvest control rule in the management plan F(2018) = (SSB(2018) B lim)/(b pa B lim) (B pa SSB(2018))/(B pa B lim), where B pa = 5, B lim = 2.5 and SSB(2018) = 3.691, expressed in million t. ^^ F lim is presently undefined for this stock. ^^^ Even with zero catch in 2018 the stock is predicted to be below B pa and MSY B trigger in Version 2: table values corrected. ICES Advice

3 Basis of the advice Table 4 Herring in subareas 1, 2, and 5, and in divisions 4.a and 14.a (Norwegian spring-spawning herring). The basis of the advice. Advice basis Management plan. A long-term management plan was agreed by the EU, Faroe Islands, Iceland, Norway, and Russia in 1999 Management plan (see Annex in ICES, 2014). ICES has evaluated the plan and concluded that it is consistent with the precautionary approach (ICES, 2013a). Quality of the assessment This year s forecast deals with the intermediate year (2017) in a different way from what was done in This is because the approach used in 2016 was forecasting substantial change in the selection pattern for the intermediate and forecast years relative to what had been estimated for the final years in the assessment, and it was unclear if such a change was realistic. Figure 2 ** Herring in subareas 1, 2, and 5, and in divisions 4.a and 14.a (Norwegian spring-spawning herring). Historical assessment results. The 2016 assessment is not included in these plots as it has been found to be erroneous. Prior to the 2017 assessment, estimates of F refer to ages Recruitment estimates from assessments conducted before 2016 are not shown as they refer to age 0 instead of age 2. Issues relevant for the advice An error in the conversion of acoustic data from the Norwegian acoustic survey on the spawning grounds survey index ( Fleet 1 ) for the period implied that abundance indices from this period were significantly underestimated in both the 2016 and 2017 assessment. The 2017 assessment has now been corrected and the current advice for 2018 provides a correction of the advice released in September Because the error also affected the catch advice for 2017 (issued in September 2016), a correction of the catch advice for 2017 is also included in this document. The correction to this catch advice is based on the corrected 2017 assessment. According to the harvest control rule in the management plan: F(2017) = (SSB(2017) Blim)/(Bpa Blim) (Bpa SSB(2017))/(Bpa Blim), where Bpa = 5, Blim = 2.5 and SSB(2017) = 4.131, expressed in million tonnes; this results in F(2017)=0.099, corresponding to catches of no more than tonnes in The reductions in the catch advice for 2017 and 2018, relative to the (incorrect) advice originally provided, are due to the fact that the corrected assessment estimates lower SSB for recent years. As a consequence, the estimated SSB is further below Bpa, resulting in lower values of F in 2017 and 2018 when the harvest control rule in the management plan is applied. ** Version 2: plots corrected. ICES Advice

4 The F in the management plan and reference points refers to ages 5 14, whereas the F from the current assessment is for ages A complete exploration of this issue is still needed. When this is done, taking into account the substantial changes that are estimated to have occured historically on the selection pattern, it will be appropriate to consider whether there are harvest strategies that are more robust to significant changes in the estimated selection in the fisheries (e.g. applying a constant selection pattern in the harvest control rule). Reference points Table 5 Herring in subareas 1, 2, and 5, and in divisions 4.a and 14.a (Norwegian spring-spawning herring). Reference points, values, and their technical basis. Framework Reference point Value Technical basis Source MSY B trigger 5.0 million t B pa MSY approach Stochastic equilibrium analysis using a Beverton F MSY 0.15 Holt stock recruitment relationship with data from ICES (2013b) 1950 to B lim 2.5 million t MBAL (accepted in 1998). ICES (2013b) Precautionary approach B pa 5.0 million t B lim exp( ). ICES (2013b) F lim Not defined. - F pa 0.15 Based on medium-term simulations. ICES (2013b) EU Faroes Iceland Norway Russia long-term management strategy Basis of the assessment Table 6 ICES stock data category Assessment type Input data Discards and bycatch Indicators Other information Working group SSB mgt_lower SSB mgt 2.5 million t 5.0 million t F mgt_lower 0.05 F mgt Medium-term simulations conducted in 2001 and ICES (2014) Herring in subareas 1, 2, and 5, and in divisions 4.a and 14.a (Norwegian spring-spawning herring). Basis of the assessment and advice. 1 (ICES, 2016a). Information from stakeholders Statistical assessment model (XSAM; ICES, 2017) that uses catches in the model and in the forecast and also includes error structures in catches and abundance indices. Assessment period : Commercial catches-at-age (stock weight-at-age from surveys and since 2009 from catch sampling). Three survey indices: Norwegian acoustic survey on spawning grounds in February/March (NASF, , ); International Ecosystem Survey in the Nordic Seas (IESNS) covering the adult stock in the Nordic seas ( ) and the juvenile stock in the Barents Sea ( ). Maturity ogive variable by year-class strength. Natural mortalities are fixed values from historical analyses (age 2 = 0.9, ages greater than 3 = 0.15). Not included, considered negligible. None. This stock was benchmarked in 2016 (ICES, 2016b). A re-evaluation of reference points and the current management plan is scheduled to take place before WGWIDE Working Group on Widely Distributed Stocks (WGWIDE) Over the last year the EU pelagic industry has conducted its fishery on the traditional fishing grounds. No changes in distribution have been observed. The fishery in 2016 and 2017 has been characterized by large shoals in both the January fishery and in the autumn season, with higher catch rates than in previous years. ICES Advice

5 History of the advice, catch, and management Table 7 Herring in subareas 1, 2, and 5, and in divisions 4.a and 14.a (Norwegian spring-spawning herring). ICES advice and landings. All weights are in tonnes. Year ICES advice Predicted catch Sum of agreed corresp. to advice quotas ICES catch 1987 TAC TAC TAC TAC No fishing from a biological point of view No fishing from a biological point of view No increase in F Gradual increase in F towards F 0.1; TAC suggested No increase in F * Keep SSB above 2.5 million t * Keep SSB above 2.5 million t Do not exceed the harvest control rule Do not exceed the harvest control rule Do not exceed the harvest control rule Max Do not exceed the harvest control rule Do not exceed the harvest control rule Do not exceed the harvest control rule * Do not exceed the harvest control rule * Do not exceed the harvest control rule * Do not exceed the harvest control rule * Do not exceed the harvest control rule Do not exceed the harvest control rule Do not exceed the harvest control rule Do not exceed the harvest control rule See scenarios Follow the management plan Follow the management plan * Follow the management plan * Follow the management plan * Follow the management plan * Follow the management plan * 2018 Follow the management plan * There was no agreement on the TAC; the number is the sum of autonomous quotas from the individual Parties. Version 3: title of column changed, previous advice values added to footnotes below. Version 2: value corrected in October 2017 (previously t). Version 2: value corrected in October 2017 (previously t). ICES Advice

6 History of the catch and landings Table 8 Herring in subareas 1, 2, and 5, and in divisions 4.a and 14.a (Norwegian spring-spawning herring). Catch distribution by fleet in 2016 as estimated by ICES. Catch (2016) Landings Discards 49% purse seine 51% pelagic trawl Discarding is considered to be t negligible, but some slippage is t known to occur. ICES Advice

7 Year Table 9 Norway Herring in subareas 1, 2, and 5, and in divisions 4.a and 14.a (Norwegian spring-spawning herring). History of commercial landings; ICES estimated values are presented for each country participating in the fishery. All weights are in tonnes. USSR/ Russia Denmark Faroes Iceland Ireland Netherlands Greenland UK (Scotland) Germany France Poland Sweden Total * * In 2006 Scotland and Northern Ireland combined. ICES Advice

8 Summary of the assessment Table 10 *** Herring in subareas 1, 2, and 5, and in divisions 4.a and 14.a (Norwegian spring-spawning herring). Assessment summary. Weights are in tonnes. Year Fishing F w F w Recruitment Rec. Stock size: SSB Rec. 2.5th SSB 2.5th Catches pressure 97.5th 2.5th age th SSB 97.5th percentile percentile (tonnes) F W (ages perce perce (thousands) percentile (tonnes) percentile 5 11) ntile ntile *** Version 2: table values corrected. ICES Advice 2017

9 Sources and references ICES. 2013a. NEAFC request to ICES to evaluate possible modifications of the long-term management arrangement for the Norwegian spring-spawning herring stock. In Report of ICES Advisory Committee, ICES Advice 2013, Book 9, Section ICES. 2013b. Report of the Blue Whiting/Norwegian Spring-Spawning (Atlanto-Scandian) Herring Workshop (WKBWNSSH), March 2013, Bergen, Norway. ICES CM 2013/ACOM: pp. ICES Herring in Subareas I, II, V and Divisions IVa and XIVa (Norwegian spring-spawning herring). In Report of the ICES Advisory Committee, ICES Advice 2014, Book 9, Section ICES. 2016a. Advice basis. In Report of the ICES Advisory Committee, ICES Advice 2016, Book 1, Section 1.2. ICES. 2016b. Report of the Benchmark Workshop on Pelagic Stocks (WKPELA), 29 February 4 March 2016, ICES Headquarters, Copenhagen, Denmark. ICES CM 2016/ACOM: pp. ICES Report of the Working Group on Widely Distributed Stocks (WGWIDE), 30 August 5 September 2017, ICES Headquarters, Copenhagen, Denmark. ICES CM 2017/ACOM: pp. ICES Advice 2017